The present invention relates generally to a signal processing apparatus and a method which allow equalizer setting operations to be performed with ease.
In the conventionally-known signal processing apparatus that handle audio signals, an equalizer (hereinafter sometimes abbreviated as “EQ”) is often used for adjusting gain (amplitude) characteristics, on a frequency axis, of an audio signal as desired by a user. Among the various conventionally-known EQs for audio signals are a graphic equalizer (hereinafter sometimes abbreviated as “GEQ”) which adjusts gain (amplitude) characteristics by dividing in advance an audible frequency range of an audio signal into a plurality of divided frequency bands and adjusting a gain for each of the divided frequency bands, and a parametric equalizer (hereinafter sometimes abbreviated as “PEQ”) in which a user designates a frequency value, a gain value and a quality factor (“Q”). For adjustment of a gain for each of the divided frequency bands, a plurality of knobs slidable, for example, in a vertical (up-down) direction are provided in the GEQ, and a user can know individual gains and approximate frequency characteristics of the gains from positions of the knobs. The PEQ has been used more and more widely nowadays by virtue of the recent popularization of DSPs (Digital Signal Processors) for audio signals. In the PEQ, the DSP performs adjusting operation for achieving a frequency characteristic corresponding to a gain value and a Q value designated as characteristic setting factors by a user, unlike in the GEQ where frequency bands are determined in advance and gain adjustment is performed for each of the frequency bands.
Generally, fundamental parameters in the EQs are three parameters: a frequency F selected for each of a plurality of frequency bands; a gain G in each of the selected frequencies F; and a Q value that is indicative of a rise variation characteristic until the gain G set in the selected frequency F is reached and a fall variation characteristic. An equalizer point (hereinafter sometimes abbreviated as “EQ point”) for each of the frequency bands is designated by such three parameters. When an equalizer curve (hereinafter sometimes abbreviated as “EQ curve”) indicative of frequency characteristics of gains is to be emphasized or de-emphasized in an equalizer point (hereinafter sometimes abbreviated as “EQ module”) having a plurality of EQ points, gain values of the EQ points are changed relatively. For such a purpose, user's operations for selecting any one of the EQ points and changing the gain value of the selected EQ point have to be performed for each of the EQ points.
Further, in the conventionally-known mixers which mix sounds etc. picked up by a plurality of microphones and send a mixed result to various recording devices (as disclosed, for example, in Japanese Utility Model Laid-open Publication No. HEI-7-42219 and Japanese Patent Application Laid-open Publication No. 2003-348683), there is employed a DCA (Digital Controlled Amplifier) technique that has a parameter common to a plurality of parameters (channel-specific fader values) and relatively changes executed values of the plurality of parameters. However, such a DCA technique has no direct relation to the EQ module.
In a case where operations for relatively changing gain values of EQ points are performed and where operators corresponding to all parameters are provided on a panel as in the conventionally-known large-size analog mixer, at least an operation for selecting an EQ point can be significantly simplified. However, with recent digital mixers where the number of operators provided on the panel is small, the operations for relatively changing the gain values of the EQ points would become more complicated. Further, although digital mixers equipped with a touch panel are also known today, such digital mixers too require the operations for selecting EQ points, and thus, the necessary operations are still complicated. Namely, in the conventionally-known signal processing apparatus, the user's operations for selecting an EQ point and changing a gain value of the EQ point have to be performed for each of the EQ points, and thus, the necessary operations cannot be performed in a simplified manner.